Insulated Concrete Forms (ICFs) are a specialized building product that has been 60 plus years in the making. At any given time there can be as many as 50 ICF companies making these forms. They come in many sizes with 4’ long by 16” tall being the most common size. So what is an ICF? An ICF is generally two pieces of Styrofoam held together with a plastic or steel tie. This product is used in place of wood or steel forms and has concrete poured into it. Unlike the wood or steel forms, the ICF is not removed after the concrete has been poured into it.
The question remains, why would someone want to use these forms? The answer is simple. ICFs provide an answer to many building problems. One such problem is fast drying concrete walls. Typical wood or steel forms are removed from the fresh poured wall as soon as possible in order to keep the form from adhering to the concrete wall. With summer temperatures reaching into the 90’s or higher, early form removal causes the concrete to dry quickly. The faster concrete dries, the more it shrinks and cracks causing the concrete wall to lose strength.
This shrinkage problem is resolved by leaving the ICF in place. The Styrofoam holds the moisture in the concrete wall, therefore eliminating shrinkage and cracking. In fact tests show that by leaving the ICF in place, the strength of the wall may be increased by as much as 50% over the desired pour strength. Other benefits include not having to remove and clean forms and less physical injuries due to the light weight of the Styrofoam. Also, since it is a Styrofoam type product, walls can be poured late into the winter season without fear of the concrete freezing.